If you have entered the wrong SIN Number and information and you are already at the REVIEW or FILE section, then you will not be able to update it. You will need to start a new return if you went to personal information and clicked on EDIT and weren't able to update your SIN. For more information on how to start a new return and delete the new one, please follow our TurboTax guide How do I delete a return in TurboTax Online?